A study is proposed with peer rejected children, who are at risk for a number of problems throughout development These problems include dropping out of school, juvenile delinquency, and adult crime. Understanding the behaviors and processes that contribute to these social difficulties is essential to the development of more effective interventions. One consistent finding in this area is that rejected children are less likely than more popular children to effectively regulate their negative affect states. The proposed study will investigate behaviors and processes related to children's emotion regulation abilities in multiple contexts. Children's attentional abilities and physiological functioning (i.e., vagal tone ) will be assessed during a baseline procedure and two cognitive tasks. The specific aims of this study are to: a) describe the emotion regulation strategies used by-rejected children in a relevant and stressful social context, entry into another's play; b) document changes in the entry strategies of rejected children after they have experienced entry failure, c) investigate the role of attentional processes and physiological functioning in the regulatory behaviors of rejected children through the use of convergent parent/teacher report and laboratory measures, and d) describe the temperamental characteristics of rejected children through these convergent measures. Fifty-two kindergarten and first grade children will be identified through peer nomination sociometric measures (i.e., 26 rejected and 26 popular). Social status will be calculated within each gender to aid in the recruitment of an equal number of boys and girls. In addition, behavioral nominations will be used to further identify rejected children with high levels of aggression.